A reliable cooling system is one of the most important systems on any outboard, and that all starts with a solid impeller. The Mercury Marine Water Pump Impeller Repair Kit - 47-803748K01 is specifically designed to restore proper water flow in 8 HP and 9.9 HP FourStroke Mercury outboards, keeping temperatures in check whether you’re trolling calm flats or pushing hard into open water.

Every component in this kit is precision-engineered to fit factory specs, so you get smooth, efficient water circulation once everything’s buttoned up. From the durable rubber impeller to the wear plate and gaskets, each part is built to withstand heat, friction, and constant exposure to water — even in saltwater or sandy environments. It’s not just about swapping an impeller; this is a complete refresh for your pump system, designed to protect your engine from overheating and premature wear.

Why this kit matters:

• Direct-fit kit for Mercury 8 HP and 9.9 HP FourStroke outboards
• Includes impeller, gaskets, wear plate, and key hardware for a full rebuild
• High-quality rubber impeller resists cracking and wear from heat and debris
• Restores proper cooling performance and protects against overheating

Best uses:

1. Replacing worn or damaged impellers after regular service intervals
2. Preventing overheating issues in sandy, silty, or saltwater conditions
3. Keeping your cooling system dialed in for reliable performance season after season

Whether it’s a routine swap or part of a larger service, keeping your water pump in top shape is one of the smartest moves you can make for your outboard — and this kit gives you everything you need to do it right.